This invention relates to a system structure recognition method for a multiloop transmission system consisting of a plurality of loop transmission groups and more in detail to a method for recognizing the structure of devices connected to form a plurality of interconnected transmission loops by means of messages circulating through the loops.
Japanese Patent Application Kokai (un-examined publication) No. Shoo 57-166756 has disclosed a multiloop transmission system, where a plurality of loops are connected to each other, and where message transmission between different loops is effected, depending on the content of data, without knowing the structure of the loops and the address of the receiver. Although this method has an advantage easily controlling which messages are to be transferred between different loops depending on circumstances and another advantage that it is not necessary to provide network control processors for the relay operation, it has a problematical point with respect to maintenance of the system, because there are no measures for recognizing at any time with what system structure this multiloop system is operated. Message transmission between different transmission control devices connected to a single loop transmission system is described in U.S. Pat. No. 4,366,479.